This invention relates to the production of carbon black. In one of its aspects this invention relates to the production of carbon black with a tint residual below -6. In another of its aspects this invention relates to carbon black reactors.
It is important to reduce the heat buildup, also called hysteresis, or rubber/carbon black compositions. Hysteresis is a measurement of how much of the elastic deformation energy put into a carbon black/rubber composition remains in the composition as heat after the deformation forces have been released. Serious accidents have been attributed to the failure of tires made from high hysteresis rubber compositions. The higher the heat buildup in the rubber compositions the greater are the chances the tires made from such compositions can be destroyed in use.
It has recently been set forth in copending application, Ser. No. 681,977, filed Apr. 30, 1976, now U.S. Pat. No. 4,071,496, incorporated herein by reference, that a rubber composition exhibiting low heat buildup along with satisfactory tread wear properties is provided in a composition comprising 100 parts by weight of rubber and 30 to 120 parts by weight of a carbon black having a tint residual of about -6 or less. Tint residual is a property of carbon black defined by the following formula: EQU TR=T-[56.0+1.057(CTAB)-0.002745(CTAB).sup.2 -0.2596(DBP)-0.201(N.sub.2 SA--CTAB)].
In this formula, the abbreviations used have the following meanings and the properties are measured as described:
TR: This is the tint residual.
CTAB: This is the surface area of the carbon black measured as described by J. Janzen and G. Kraus in Rubber Chemistry and Technology, 44, 1287 (1971), m.sup.2 /gm.
N.sub.2 SA: This is the surface area of the carbon black measured using nitrogen in accordance with the ASTM method D-3037-71T, m.sup.2 /gm.
DBP: This is the structure of the carbon black in cc/100 g and is measured in accordance with U.S. Pat. No. 3,548,454 and, after crushing, by method B in accordance with ASTM D-2414-70. This property is also referred to as 24M4 DBP.
T: This is the tint or tinting strength of the carbon black measured by arbitrarily assigning the reference black IRB No. 3 the value of 100; the tint is measured in accordance with ASTM 3265-75.
It is therefore an object of this invention to provide an apparatus suitable for preparing carbon black having a tint residual of -6 or less. It is another object of this invention to provide a method for producing carbon black having a tint residual of -6 or less.
Other aspects, objects, and the various advantages of this invention will become apparent upon study of this specification, the drawings, and the appended claims.